Selective filter system



Jan. 17, 1933. A. M. TROGNER SELECTIVE FILTER SYSTEM Fil y 1951 2 Sheets-Sheet m; Q NM Q;

INVENTOR IJIIEI' ATTQRMEY wN MN NN \N Jan. 17, 1933. A. M. TROGNER SELECTIVE FILTER SYSTEM 2 Sheets-Sheet INVENTOR A gthur M. TI'DHIIEI ATTORNEY Filed May 26. 1931 Patented Jan. 17, 1933 UNITED STATES PATENT OFFICE ARTHUR M. TROGNER, 0F MAPLEWOOD, NEW JERSEY, ASSIGNOR TO WIRED RADIO, INQ, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE SELECTIVE FILTER SYSTEM Application filed May 26, 1931. Serial No. 540,035.

My invention pertains in general to band pass electric filter systems and specifically relates to a type of filter system having switching means for rendering the filter system selectively responsive to predetermined frequency bands.

In Robert D. Duncans, Jr., co-pending application, Serial Number 495,823, filed November 15, 1930, there is disclosed a type of filter system which can be made selectively responsive to different bands of frequencies by a switching mechanism which selects related values of circuit constants. The switching system disclosed in this co-pending application comprises a series of switches each of which is adapted to connect to any one of several predetermined values of constants of any single mesh of the series of meshes comprising the filter system. Such an arrangement necessitates the movement of all switches to make the filter system responsive to a different frequency band.

One of the objects of my invention consists in providing a selective filter system in which it is necessary to move but one switch to change the constants of a series of meshes in a filter.

Another object consists in providing a selective filter system having a serles of switches each of which connects to related values of circuit constants in a multiplicity of filter meshes.

A further object comprises producing a selective filter system having simple mee ehanical means for controlling the circuit constants of an electrical circuit.

I accomplish the above desirable objects in a novel selective filter system employing a series of rotatable switches under control of a reciprocative member.

In the drawings which accompany and form a part of this specification and in which like reference characters designate corresponding parts throughout:

' Fig. 1 is a diagrammatic representation of the selective filter system of my invention;

Fig. 2 is a top plan view of the switching mechanism employed in my system; and

Fig. 3 is a transverse sectional view along the line 3--3 of Fig. 2.

Referring to the drawings in detail, and particularly to Fig. 1, input terminals 1 are connected through coupling condensers 2 to a potentiometer resistance 3. The potentiometer resistance 3 is connected to an output terminal 4 and has an adjustable connection to an autotransformer 6. A plurality of switches 7, 8, and 9 are provided with contacts 10, 11, and 12 as shown. Contacts 10 are connected to different values of the inductance comprising autotransformer 6. Contacts 11 are commonly'connected to ground and to the output terminal 4. Contacts 12 in switch 7 are respectively connected capacitance values,

An inductance 25, connected to the autotransformer 6 and electromagnetically coupled to an inductance 26, is connected to capacitances 13, 17, and 21. An inductance 27, connected to inductance 26 and electromagnetically coupled to inductance 28, is

connected to the capacitances 14, 18, and 22. An inductance 29, connected to inductance 28 and electromagnetically coupled to indutance 30, is connected to capacitances 15,

19, and 23. One side of the inductance 30 is connectedto the capacitances 16, 20, and 24, while the other side of the inductance 30 is connected through a terminating impedance 31 to contacts 11 of the switches 7, 8, and 9.

The inductances 26 and 28 also have connections, as shown, to ground.

The inductance 25 forms a resonant circuit on combination with any one of the capacitances 13, 17 or 21. The inductances 27 and 26, in combination with any one of the capacitances 14, 18, or 22, form another resonant circuit, while the inductances 28 and 29 in combination with any one of the inductances 15, 19, or 23 form another resonant circuit. The capacitances 16, 20, and 24 provide different values of capacitances cffective in combination with the inductance 30 and terminating impedance 31. This chain of resonant circuits, having the properly terminated impedance 31, forms a filter system which is responsive to any one of a plurality of predetermined frequency bands depending upon the values of capacitances selected.

The switches 7, 8, and 9 are provided with rotor contacts '32 for making connection with p the switches 7,8, and 9 to be actuated one at the contacts 10, 11, and 12. Accordin'g'to my invention any one of the rotor contacts 32 can be moved for rendering the filter systerm, as a whole, selectively responsive to a predetermined band of frequencies.

Fig. 2 is a view of the mechanical construction of the switching arrangement of myselectivefilter system. Referring to Figs. 2 and 3, the rotor contacts 32 aremounted upon rotatable insulating members 33 mounted uponpivots 34. The pivots 34 are secured to an insulating base member 35. The contacts 10, 11, and 12are mounted upon the basemember 35 for engagement with the rotor contacts 32. V

Tension springs 36 are provided between the rotatable members 33 and pillars 37 for normally holding the rotatable members 32 in a positionsuch that therotor contacts are out of engagement with the contacts 10, 11. and 12. A bar 38 is'reciprocatively mounted in two bearing members 39-and 40 in a positionabove the rotatable members 33. A knob 41 rotatably mounted in bearing member 42 is provided with anarm 43 which has a slot thereinfor engagement-witha pin :44 mounted inthe bar,-38. The arm 43-terminates in a pointer 45 for indicating the position of the bar 38 with reference to designations A, B, and C on an index sector 46,

The bar 38 is provided with projecting portions 47, 48.; and '49 for engagement with pins 50 mounted in therotatablemembers 33 of switches 9, 8,-and 7. The projections 47, 48, and 49 are so situated-along the" bar 38 that longitudinal movement of the bar 38 will cause sequentialengagement of the projections 47 48, and 49. with the pins 50 of the switches-7, 8, and 9. That is. when the knob 41 is moved to a position such that the pointer 45 is opposite theidesig-nation A, the projecting portions 47 will bemoved into engagement with pin 50 of-switch9 so that the rotatable member 33 is rotated to cause the rotor contact 32-thereofto engage-with the contacts 10, 11. and 12. Movement of the pointer 45 to the designation B will cause the projecting portion 48 to engage pin 50 of switch 8 thereby moving rotatable member 33 to cause the rotor contact-32 mounted thereon to engage with contacts'10. 11, and 12. At the same time, the projecting portion 47 will be moved out of engagement with pin 50 thereby permitting tension'sprinjg 36 "the contacts 10, 11, and 12. Movement of the ointer 45in a reverse direction'willcause a time in reverse order. Each of the switches '7, 8, and '9 is adapted to respectively control the groups of circuit constants of the filter system cooperating to make the filter system responsive to a predetermined band of frequencies. The bar 38 is adaptedto sequentially operate these switches by reciprocative motion.

It will be evident that the selective filter system of my invention provides an eflicient and practical method of switching which is very adaptable .to manufacturing purposes such as in the construction of wired radio receivers employing selective filter systems coupled to power lines carrying program modulated high frequency energy. at a plurality of different carrier frequencies. Although I have shown a preferred embodiment of my invention, I donot wish tobe limited thereto except insofar as may :be pointed out in theappended claims.

What I claimas new. and originaland desire tov secure by LettersPatent of the United States is: I

1. A selective filter system comprising, a plurality of circuits each having a plurality of diflerent values of circuit constants, apluralityof switches each ofwhich isconnected to a plurality of-said circuit constants in several of said circuits, and common mechanical means for actuating all of said switches in apredetermined sequential order.

2. In a selective filter. system, a filter system having a, plurality of groups of capacitances, each of saidgroups of capacitances being adapted to render said filter system responsive to a different frequency band, a plurality of switches each of which is adapted to control one of said groups of capacitances, and common mechanical means for operating said. switchesin sequential order to render said filter system. selectively responsive to predetermined bands of frequencies.

3. A selective filterusystem comprising,'a plurality of resonant circuits each having inductance and a plurality of predetermined values of capacitances, a plurality of switches each of which is connected to one of the capacitances in allof said resonant circuits, and common mechanical means for sequentially operating said switches.

'4. A selective filter system comprisingga pluralityv of circuits each having aplurality of different predeterminedwaluesof circuit constants, a plurality of switches each of which is connected to related groups of said values of circuit constants, and a reciprocative member for actuating said switches in a predetermined sequence.

5. A selective filter system comprising, a plurality of circuits each having a plurality of different values of circuit constants, a plurality of switches each of which is adapted to render related groups of said values of circuit constants simultaneously effective in said plurality of circuits, and a reciprocative member for imparting rotary motion to said switches in predetermined sequence.

ARTHUR M. TROGNER. 

